1. Field of the Invention
The present invention relates generally to the field of integrated circuit design, and specifically, to signal recording and playback systems.
2. Background Information
The ISD 5008 device of Information Storage Devices, located in San Jose, Calif., represents a 3-volt serial interface family of voice recording and playback devices. This device is a fully integrated single-chip solution which provides seamless integration of enhanced voice features for digital cellular phones (GSM, CDMA, TDMA, PDC, and PHS), automotive communications, GPS/navigation systems, and portable communication products. The device enables customers to quickly and easily integrate 4 to 8 minutes of voice storage features such as one way and two-way (full duplex) call record, voice memo record, and call screening/answering machine functionality. The ISD5008 integrates the sampling clock, anti-aliasing and smoothing filters, and the multi-level storage array on a single chip.
However, the prior art devices can only store analog information. In many applications where digital data associated with voice processing functionalities are available (e.g., telephone book numbers, system configuration parameters, message address pointers), the prior art devices require additional digital storage devices with complicated external circuitry and interfacing (e.g., hardware and programming) effort. In addition, the prior art devices employ at least a 4-wire interface bus, causing increased pin count and complex interfacing circuitry to other devices and/or processors.
Therefore, there is a need to provide integrated digital and analog storage in a record and playback device having efficient bus interface.